Track circuits with battery charging or depolarizing means



H. L. BLACK TRACK CIRCUITS WITH BATTERY CHARGING Aug. 31, 1948.

OR DEPOLARIZING MEANS Filed Dec.

)l-A T15 Patented Aug. 31, 1948 TRACK CIRCUITS WITH BATTERY CHARG- ING0R DEPOLARIZING MEANS Harry L. Black, Moncton, New Brunswick, Canada,assignor to General Railway Signal Cornpany, Rochester, N. Y.

Application December 20, 1944, Serial No. 568,991

14 Claims.

This invention relates to track circuits and more particularly to trackcircuits which are frequently occupied for appreciable periods bystanding trains.

Track circuits which are located near loading platforms or on the sidetracks of passing sidings frequently have a train standing thereon for aconsiderable time which may result in the draining of the track batteryto an extent to result in the supply of insufficient current to pick upthe track relay after the train leaves the track circuit. This is trueirrespective of whether the track battery is a storage battery or aprimary battery; and if a storage battery, itis true even though thisstorage battery may be connected to an alternating current sourcethrough trickle charge rectifying means. If it is a primary battery, thecost is also prohibitive.

In accordance with the present invention, it is therefore proposed tosupply the track circuit with current through the medium of a rectifierfed from an alternating current source so long as alternating current ispresent and to use the flow of direct current from such rectifier to thetrack rails for the purpose of charging or discharging the battery at avery low rate in the case of a storage battery or a primary battery,respectively. It is also proposed to connect such battery across thetrack rails during a cessation of alternating current, To prevent theflow of excessive charging current through such storage battery while itis included in series with the rectifier circuit it is proposed, as afurther object of the present invention, to apply a shunt resistanceunit of predetermined resistance around the battery so that not all ofthe current which fiows to the track rails will flow through thebattery, in that part of this current will flow through such shuntresistance. Stating this in different words, the track circuit ispreferably fed by current from the rectier through a circuit including aresistance unit and the battery is then charged or discharged, as thecase may be, by, or dependent upon, the voltage drop across saidresistance unit.

Since the battery and the shunt resistance in multiple therewithrepresents a substantial amount of resistance, especially when thebattery is a primary battery, this resistance may serve as a seriesresistance for the track circuit. During cessation of the alternatingcurrent, however, a series resistance is preferably included in serieswith the battery in accordance with another object of the presentinvention and the shunt resistance which was originally connected inmultiple with the battery is preferably removed dura ing the cessationof the alternating current as determined by a power-ofi` relay.

Other objects, purposes and characteristic features of the inventionwill in part be pointed out in the specification and will in part beobvious from the accompanying drawings in which:

Fig. 1 shows one form of the invention; and

Fig. 2 shows a modified form of the invention.

Structure.--The track section comprises rails I, insulated from theadjacent track by insulating joints 2, and may be located at a loadingplatform or comprise part of a side track which is frequently occupiedfor appreciable times by a standing train. This track section ispreferably track circuited by apparatus including the usual bondedrails, a track relay TR, and the track source more specificallydescribed hereinafter. In the usual track circuit the track battery TBwould be connected across the track rails through the medium of wirespreferably including a series resistance as is at times true of thestructure shown in the drawings. Under normal conditions, however,applicant proposes to supply current to the track circuit including thetrack relay TR from a rectifier R, deriving its in-put alternatingcurrent through an adjustable reactance 4 from a secondary winding l0 ofa transformer Tr, the primary winding Il of which is connected to analternating current source AC'. Instead of supplying direct currentenergy directly from this rectifier R to the track rails, it is proposedto connect the track battery TB in series therewith with the polarity ofthe battery TB so poled in the circuit that the out-put voltage of therectifier R and the voltage of the track battery TB oppose each other,that is, so that the track battery TB is included in series with therectifier R in bucking relationship. The voltage delivered by therectier R is higher than the voltage of the battery TB so that thebattery can be charged, if desired, as will be true if a storage batteryis used. It should however be remembered that storage battery chargingtakes place, in considerable volume, only when the track circuit isshunted by a train under which condition its resistance is substantiallyzero, for this reason the out-put voltage of the rectifier R need not bemuch higher than the voltage of the battery TB. When a primary batteryis used the rectifier out-put voltage may be lower than when a storagebattery is used but it should still be higher than the Voltage of suchprimary battery.

From this structure it is readily seen that since the current suppliedto the track circuit by the rectifier R, and illustrated by solidarrows, flows in a direction from left to right through the resistanceunit Tl, that it is the ohmic value of this resistance, in combinationwith the track circuit current flowing, that determines whether theb-attery TB will be charged or discharged. In the event the battery TBis a storage battery the resistance 'of the unit Tl will be high enoughto cause the battery to be charged at the vminimum possible rate to takecare only of occasional alternating current failures. If the battery TBis a primary battery, such as a vpotash battery, the ohmic value ofresistance unit rl is decreased to a value whereby the track circuitcurrent flowing therethrough will not quite produce enough voltage dropto cause charging of the battery and' to actually cause lightdischarging of the battery. A primary battery requires a `lig-ht loadthereon, that is, a small discharge, to keep i't i'n goodworkingcondition by keeping it continuously l'depolarized. A storage battery,on the other hand, requires chargingr at -a very low rate to Ikeep it ingood condition andfully charged.

L'et us now give consideration to voltage relationships and resistanceswhen the power-oi relay PO assumes its energized-.position and the trackcircuit is unoccupied. Under conditions as illustrated in the drawings',that is with no train in the track section, there is no seriesresistance unit, such as ,-i-s ordinarily used, included in the tra'ckcirc-uit unless the resistance unit rl were 3 considered to be suchaseri'es resistance unit. For thisreason the resistance of the trackcircuit con-'- sisting-only of the resistance of the tr-ack rails andthe track lrelay TR in'A series is very low. The

ohmic resistance of the usual series resistance y unit -of a trackcircuit is yabout three times that of the resistance of the track railsand track-relay inseries. -In yother words, the voltage drop across thetrack rails with the power-#oir relay POI in itsl attracted positionisyonly about 25 vper cent that ofthe voltage drop across the ent-iretrack circuit includingthe ,series resistance r2, the-track rai-ls Iyand the track relay TR. in series. For this reason the voltage dropacross the track rails with the frelayvPO` in its attracted position isalcol-1h25 per cent that fof the Voltag'edeliveredby the battery TB andthe voltage y"delivered by the rectifier R is about 125 per 'cent thatyof the voltage delivered by thejtrac-k battery TB;

This power -of relay .PO -isenergized from the fsecondary windingV l3gofthe transformer T1 and remains -in-its energized posi-tion` so long -asalternating current isavailable but drops to its deonergize'd positionupon a cessation in the supply of alternating current. Deenergzation ofthis power-offv relay 'PO causes the iront contact VI2 thereof toppen tothereby `remove the shunt Iresistance rl and causes the back contact-If2 to fclose toy thereby shunt the out-put -side of the rectifier Rthrough a shunt circuit including-the series resistance unit r2. Withthe rectifier R shunted as justfpoin-ted out the track battery TB isconnected directly across the track rails with the series resistancerzincluded in series therewith. The `resistance of the rectifier Rinmultiple with this resistance r2 is so high that it may be dis--`regarded. l

Obviously, if desired, the rectifier R .may beentirely disconnectediromthe track circui-t instead of shuntin-g the rectifier yRash-1st pointedout. A Llso, if desired, the track battery TB' may upon the cessation ofalternating ci'i-rrfent be connected across the track 1rails -insuchlpolarity'relationship that the current supplied to the -traokcircuit flows lin the same'directi'on through the track rails'condition, as illustrated in the drawings, current is supplied to thetrack circuit including the track rails i 'and track relay TR through acircuit which` may be 'traced from the positive terminal of therectifier R, wires 7l-d` and I5, front contact l2 of the powereo' relayPO, resistance unit rl, wires I6 and l FI, track fraii'l l, winding ofthe track relay TR. other track -rail l, wires I8 and I9, to thenegative terminal o 'rectier R. The ow of this current through theresistance unit rl' causes a potential drop which slightly exceeds thevoltage of the track battery TB in the case of a storage battery so thata smal-l 'amount `of current -also flows in a charging direction throughthe track battery TB. In this connection it is desired to point out thatthe resistance unit Ar/I' which is preferably adjustable is so adjusted`as to provide the desired average charging rate for the track batteryTB. If the .battery TB, on the other hand, is oi `the primary type theohmic value of the resistance TI is small enough to cause a lslightdischarge of the battery -as -is-desirable, to cause depolarization ofthe battery.

`Let us now assume that the track circuit under consideration becomesoccupied. Under this condition th-e flow of current from the rectifier Rto. the track rails is greatly increased and this increasedcurrent-flowsat least in` part through the track battery TB so that this track:battery TB, in the event itis -a storage battery, has curr-entflowingin a charging direction zat `a .higher rate as is also true rin the caseof a primary battery except that `such primary battery would not -bematerially charged =by the flow of such current. `Since the cur-rentwhich actually `iiows through the track 4battery' TB is dependent uponthe internal resistance of the track battery and also upon theresistance of the -unit rl, and since the total char-ging of theybattery TB Iat the higherrate depends upon the duration of occupancy ofthe tra-ck circuit the resistance unit rl will in .practice be soadjusted as to allow :suicient charging or discharging 'of the batteryTB, depending on the kind of battery used, so as -to `maintain thebattery Iin* .good kworking condition.

-Let ns now :assume that an alternating current power failure takesplace `and .that the cessation of flow of `alternati-ng current causesthe poweron 1relay PO to assume its deenergized position, under whichcondition 'its front contact l2 is opened-and its back contact II2, isclosed. Under this condition the track xbattery TB supplies :current of-inverse polarity to the track rails througha circuit which may betraced-.from the positive terminal of thebattery T-B, wire l5, backcontact |-2y of the power-oirr relay PO, wire `2ll, resistance unit r2.,Wire I8, track rail l, winding of thetrack relay TR, other track fra-il`l, wire I1, and to the, negative termi-naief the track Abattery Theflow 'of this current has been indicated by dotted arrows. The 'ohmicValue of the resistance r2 zis so chosen fasv to produce safe 4trackrelay operatingA margin-s dur-ing the cessation `of alternating currentpower when all of ithe current supp-lied, to the :track rails is derivedfrom the ltrack ,battery TB. `Ii the 'track :relay TR1-is aneutral'srelay the structure as illustrated in Fig. 1 is satisfactory inthat the pole changing of the track circuit current does little harm.Should it, however, be desirable to employ a, polar track relay ofeither the two-position or three-condition type in place of the oneshown an additional contact would have to be provided on the power-offrelay PO so as to connect the track relay TB across the track rails insuch polarity relationship as to cause current to ow through the trackrelay TR in the same direction during an alternating current powerinterruption as flows with the power-off relay PO in its normalenergized position. Such contact and circuit structure has beenillustrated in Fig. 2 of the drawings where contacts 22 and 23 perform apole changing function in addition to the switching function performedin Fig. 1 by contact I2.

Having thus shown and described two forms of the invention it is desiredto be understood that these forms of the invention have been selected toillustrate the underlying principles of the invention, and apparatuswhereby these principles may be carried out, and it should be furtherunderstood that various changes, modifications and additions may be madein practicing the invention without departing from the spirit or scopeof the invention so long as these changes do not depart from the scopeof the following claims.

What I claim is:

1. Track circuit structure of the type described comprising, a tracksection, a battery for one end of said section, a track relay connectedacross the track rails at the other end of said section, a source ofalternating current, a rectier connected to rectify current from saidsource to deliver a voltage higher than the voltage of said battery, anda power-oir relay normally energized from said alternating currentsource for during the presence of alternating current causing directcurrent to now from said rectier to the track rails at said one end ofsaid section through a circuit including said battery in buckingrelationship and for during the cessation of alternating current fromsaid source connecting said battery directly across the track rails atsaid one end, whereby said battery is at times charged through a circuitincluding said track relay.

' 2. A pair of track rails, a source of alternating current, a rectierfor rectifying current from said alternating current source, a batteryof lower voltage than the voltage delivered by said rectier, a power-offrelay connected across said source of alternating current, a frontcontact on said relay for connecting said rectier across the track railswith said battery in bucking relationship in series therewith, and aback contact on said relay for connecting said battery across the trackrails in a polarity direction to cause current to ow in the samedirection in the track rails when said relay assumes its deenergizedposition.

8. A pair of track rails, a source of alternating current, a rectifierfor rectifying current from said alternating current souce, a battery oflower voltage than the voltage delivered by said rectier, and apower-off relay connected across said source of alternating current andincluding means for connecting said rectifier across the track railswith said battery in buckling relationship in series therewith when saidrelay assumes its energized position and for connecting said batterydirectly across the track rails when said relay assumes its deenergizedposition.

LA pair of track rails, a source of alternating current, .a rectier forrectifyingcurrent from said alternating current source, a battery oflower vol-tage than the voltage delivered by said rectier, and apower-off relay connected across said source of alternating current andincluding means for connecting said rectier and battery in vbuckingrelationship in series and across the track rails when said relayassumes its energized position and for connecting said battery acrossthe track rails when said relay assumes its deenergized position.

5. IIn a track circuit, the combination with a pair of vtrack rails, abattery, an alternating current source, a rectifier connected to rectifycurrent from said source at a higher voltage than the voltage of saidbattery, a resistance unit, and a power-off relay means for connectingsaid rectier and said battery in bucking relation-ship in series andacross said track rails and connecting said resistance unit in multiplewith said battery when said relay means assumes its energized conditionand for connecting said battery across the track rails when said relaymeans assumes its deenergized condition.

- 6. In a track circuit, the combination with a pair of track rails, abattery, an alternating current source, a rectifier connected to rectifycurrent from said source at a higher vol-tage than the voltage of saidbattery, a first resistance unit, a second resistance unit, and apower-off relay, means for connecting said rect'ier and said battery inbucking relationship in series and across said track rails andconnecting said first resistance unit in multiple with said battery whensaid relay means assumes its energized condition and for connecting saidbattery in series with said second resistance unit and across the trackrails when said relay means assumes its deenergized condition.

7. In a track circuit; the combination with a pair of track rails; astorage battery; a source of alternating current; a rectier connected torectify current from said source; a resistance unit; and a power-oir`relay means for connecting the output leads of said rectifier across thetrack rails in series with said resistance uni-t and said battery inmultiple when sai-d relay assumes its energized position,v saidresistance unit having a resistance of ohmic value such that the batteryis charged by the voltage drop across said resistance unit so long assaid relay means assumes its energized position, and for connecting saidbattery across said track rails when said relay means assumes itsdeenergized position.

8. In ahtrack circuit; the combination with a pair of track rails; astorage battery; a source of alternating current; a rectier connected torectify current from said source; a first resistance unit; a secondresistance unit; and a power-off relay means for connecting theoutput-leads of said recti'er across the track rails in series with saidrst resistance unit and said battery in multiple when said relay assumesits energized position, said resistance unit having a resistance ofohmic value such that the battery i-s charged by the Voltage drop acrosssai-d resistance unit so lon-g as said relay means assumes its energizedposition, and for connecting sai-d battery in series with said secondresistance unit across said tra-ck rails when said relay means assumesi-ts deenergized position.

9. In a track circuit; the combination with a pair of track rails; aprimary battery; a source of alternating current; a rectifier connectedto rectify current from said source; a resistance unit;

:and Aa power-ofi .relay means 'for when 4in an en'- ergized conditionconnecting the output leads of said rectier in a series circuitincluding said resistance unit and battery in multiple .and includingl.the track rails, said resistance unit having a .resistance of ohmicvalue such that the baitteryiis discharged through said resistance uni-trso long as said relay meansassumes its energized position, and :forconnecting said battery zacross sai-d track rails `when said relaylmeans assumes its .deenergized condition.

10. In a track circuit.; the combination `with a pair of track rails; aAprimary battery; a source of alternating current.; a rectifierconnected to rectify `current from 4said source; a rst resistance unit.;a second resistance runit.; and a power-oli relay means fo-r when in4 anenergized condition connecting the out-put leads ofsaid rectier inseries with said first resistance unit and said battery in multiple andacross the track rails, said resistance unit having a resistance ofohmic value such that the battery is discharged ythrough said firstresistance unit lso lon-g as said relay means assumes its energizedposition and for connecting said battery in :series with sai-d Isecondresistance unit across said track rails when said relay means assumesits deenergized condition.

1l. In a track circuit., .the combination with a pair of track railsforming a track section and having a track relay -connected across therails at one end, a source of alternating current, a rectier, .apowereoff relay, rst and .second resistors, and a storage batterylassociated with the other end of said track section, circuit means fornormally supplying `energy to said power-oid relay from.sa-idalternating current sour-.ce so las to pick up its contacts butacting upon :a failure of said source .to deenergize said power-o relayso as to allow its contacts to drop away, circuit means for supplying.energy from said alternating source tothe input of said rectier forsupplying an output with a voltage slightly higher than the .voltage ofsaid storage battery, circuit means .for vconnecting the output of saidrecti-er across the rails .of said track section .at vsuch other end inseries with said storageibattery with :its polarity in opposition,circuit Iconnections .including a front Contact of .said power-oli relayfor connecting said ir-st resistor in multiple with said 4battery tothereby limit the .chargingrate of Isaid f Storage battery to anormalvalueswhile said track section is unoccupied, 'other circuit meansincluding ,a back contactof said power-.off relay .for connecting saidsecond resistor .inseries Withsaid battery across. the vrails of .saidsection at such other end when said 'power-off vrelay is Acleene-rgized,vwhereby the normal .charging rate of said storage battery is determined.by .the `yaluevof said rst resistor and both said first resistor andsaid batteri/.act as limiting resistors when lthe track section is.occupied by .a train so long as said alternating `current source Iis.supplying the energy, and whereby rsaid second resistor serves as alimiting resistor when track section is -occupied by a train Wheneversaid alternating-cure rentsource fails to supply energy.

12. In a track circuit, .the combination with a pair of track railsforming a trac-k section and having .a track relay connected across therails at one end, a source of alternating current, a rectier, apower-off relay, first and .second resistors, and apr-imary batteryassociated .with the other end of said track section, circuit means forconnecting said power-off relaytosaid alternating current source tocause its contacts .to

f8 pick up'wvinle energy .is supplied'but .acting upon failure 'of .saidsource to supply energy to .allow its .contacts to drop away, circuitconnections for supplying energy .from said .alternating cur rent source-to vthe input of said rectifier forsuip- .plying a direct .currentoutput yhavin-g .a potential .slightly higher ythan rthe'potential of.said pri mary ibattery, circuit means connecting the loutputiofsaidrectifier across the rails of .said .track section at such other .end in.series with said vprimary battery withits polarity in opposition,:cir-- cuit means tincluding za front contact .of said .power-off rel-ayfor :connecting said rst `resistor in lmultiple with said vprimarybattery when said .power-off relay is energized .to thereby provide a:path for .the .energy supplied to .said track circuit `.from Isaidrectiier under normal unoccupied conditions of said track section tof.such fa value .as to Iprovide va -,potential -dropacross .such rstresistor slightly less than the potentialI .of said .primary battery to:allow a small .normal discharge of said |pri-mary battery, .and .othercircuit means including a back contact .of said power-oir relay forconnecting said second resistor-'inseries with said `battery across therails of said track section at suc-h other fend vwhen said power-olirelay is deenergized, whereby the normal `discharging rate of said`primary battery is determined -by said `first resistor and both saidrst resistor and said primary 'battery act as limi-ting resistors withrespect to theoutput of said recti-er when the track section is occupiedby a train during the supply of power from said alternating currentsource, and whereby said second `resistor serves as a limiting resistorwith respect to said pri-mary battery -when Asaid track section isoccupied by a train during the failure of said alternating currentsource to supply power.

13. In atrack circuit of the Atype described, the combination with apair of track rails, a ldirect current track relay connected across thetrack rails at one end, a source of alternating current at .the otherend, a power-off .relay connected to and energized 'from said source, arectifier, :a trackbattery, .and circuit means for connecting saidrectier so as to rectify current from said source and apply rthe rectiedcurrent .to said other .end of the .track rails through .a :partialcircuit including said .track .battery in series in a ,polaritydirect-ion so as vto .be charged ,by the rectified current when saidpower-off relay `is in an energized condition and -for connecting sai-d.battery across .the track rails at .such other end when said `power-oir.relay is in itsdeenergized condition. l

:14.1111 a .tr-ack circuit of the type described, the combination with.a .pair of track rails, .a direct current `track relay connected across.the `track rails .atene vend, a source of alternating current at theother end, a power-oli relay connected te and energized from saidsource, a rectifier, a track battery, and circuit means for connectingsaid rectifier so as to rectify current from said source and apply -.the.rectified current .to said other end `.of the Atrack rails .through apartial circuit .including .said track battery i-n series` yin apolarity .direction so as to :be charged-by `the rect-ined current whensaid power-oil relay isi-n an energized `condition and for connecting.said battery across the trac-k rails at such .other .end when `saidpower-off relay is :in its deenergized condition and in a polaritydirection :such that current .flows inthe same direction in the ltrack 9rails as it did when said power-01T relay assumed its energizedcondition.

HARRY L. BLACK.

REFERENCES CITED The following references are of record in the le ofthis patent:

Number UNITED STATES PATENTS Name Date Zierdt May 12, 1931 Willing Sept.22, 1931 Gilson July 4, 1933 Nicholson June 30, 1936 Gilson Aug. 31,1937 Williamson Dec. 7, 1937

